You can get a clear sense how the lava just flows out of new fissures (cracks) that form on the volcano before the eruption starts (see above). This is all part of the sequence of events related to Hawaiian-style volcanism. If the eruption persists like we see at Kilauea or Holuhraun, the linear array of vents coalesce into a a few vents that focus the eruption, but at first, lava can erupt along the length of these fissures (in this case, about 500 meters).